For homemade ricotta: Pour the milk into a large pan, add a pinch of sea salt and put over a medium heat. Allow the milk to heat up slowly, stirring from time to time.
Just before it comes to the boil (steam and small bubbles begin to appear on the surface, thermometer reading between 82C-85C) remove from the heat, add the vinegar and stir gently. You will see curds starting to form. Continue to stir for 1 minute or so.
Cover with a clean cloth and allow it to sit for a couple of hours. Once the ricotta has rested, line a colander with a large piece of muslin and put this over a larger bowl or pan.
Spoon the ricotta into the colander and allow it to drain for an hour or so, or overnight depending on your desired firmness. For the baked ricotta, let it drain for around 4 hours.
To test whether the cheese is ready, gently lift the muslin up by the corners and twist lightly - the liquid should be slightly milky in colour.
For baked ricotta with lemon, thyme & chilli: whisk the ricotta, lemon zest, thyme, rosemary, salt and chilli flakes together.
Transfer to a baking dish and sprinkle with the grated parmesan.
Bake for 15 minutes at 190C.
Sprinkle with sea salt and finish with a drizzle of extra virgin olive oil. Serve with croutons.